With advances in modern microelectronics and microprocessor technologies, especially emergence of the LSI (Large Scale Integrated Circuit) and programmable logic devices, conventional radio technologies is based mainly on hardware have made great strides. Developments in hardware, such as DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array) and GP (General-purpose Processor), and the introduction of the computer bus, lead to significant changes in the radio architecture and the birth of SWR (Software Radio) as a new technology. Since the software radio technology can be adapted to different standards by using different software and alters the channel access scheme or the modulation scheme by adjusting the software setting, flexible communication terminals can be developed so that a terminal may be used in mobile networks with different schemes, thus bringing convenience to the subscriber and decreasing cost for the operator, which prompts the development of mobile communication technologies.
The software radio, in its nature, refers to a radio platform with complete programmability and most flexibility. Complete programmability involves programmable RF (Radio Frequency) bands, channel access schemes and channel modulations. An optimum software radio should have the capability for RF digital access. The concept of software radio is introduced to implement the required radio system on an open common hardware platform by using different programmable software methods. Unfortunately, the requirement for complete programmability cannot be met yet under current technical conditions. SDR (Software Defined Radio) technology thus emerges, which refers to the software radio realizable under the current technical conditions and is considered as the software radio with IF (Intermediate Frequency) programmable digital access capability.
In a SDR terminal, the programmable hardware can perform different functions based on the respective configuration information. It is, therefore, a crucial technical issue in SDR as how to configure the terminal hardware. A configuration scheme for SDR is described in an U.S. application for patent with Publication No. 2005/0059427 A1 , entitled “System and Method for Configuring a Software Radio” filed by Robert Leon Wallace on Sep. 15, 2003. In the scheme proposed in the patent application, a SDR device uses a programmable generic hardware platform, with all configuration information stored in a smart card. The configuration information includes various communication protocols, MODEM (Modulation and Demodulation) schemes, digital signal processing protocols, CODEC (Coding and Decoding) schemes and etc. The SDR device may configure the programmable hardware platform through reading the configuration information from the smart card to perform different functions, so as to configure the SDR device as a corresponding communication device as desired, for example, a CDMA (Code Division Multiple Access) mobile phone or a GSM (Global System for Mobile Communications) mobile phone. The scheme fully dependent on software to program the generic hardware is termed as complete software configuration scheme.
Although the above-mentioned complete software configuration scheme has great flexibility in theory, it's very hard to spread to business field in practical applications. Taking the most common programmable hardware FPGA as an example, it's expensive, as well as bulky and power-consumptive, which limits its use within research or military fields. Even without consideration of price and cost, it will still be very hard for FPGA to find applications in commercial mobile terminals, because its bulk and power consumption cannot meet the requirements of portability and limited battery capacity for mobile terminals. In addition, the configuration information will reach a large amount if all functions are embodied in the configuration information through software programming. When the configuration information is loaded into the SDR terminal device through reading the smart card or over-the-air download, there will be higher requirements for the memory capacity, card reading speed or download speed for the SDR terminal device.
From the above analysis of the full software configuration scheme, it can be seen that the complete software configuration scheme currently is only an ideal solution and has no feasibility due to some factors such as cost, power consumption and bulk.